import gzip
import logging
import os
import shutil
import time

from autotest.client.shared import settings
from autotest.server import utils

# import any site hooks for the crashdump and crashinfo collection
get_site_crashdumps = utils.import_site_function(
    __file__, "autotest.server.site_crashcollect", "get_site_crashdumps",
    lambda host, test_start_time: None)
get_site_crashinfo = utils.import_site_function(
    __file__, "autotest.server.site_crashcollect", "get_site_crashinfo",
    lambda host, test_start_time: None)


def get_crashdumps(host, test_start_time):
    get_site_crashdumps(host, test_start_time)


def get_crashinfo(host, test_start_time):
    logging.info("Collecting crash information...")

    # include crashdumps as part of the general crashinfo
    get_crashdumps(host, test_start_time)

    if wait_for_machine_to_recover(host):
        # run any site-specific collection
        get_site_crashinfo(host, test_start_time)

        crashinfo_dir = get_crashinfo_dir(host)
        collect_messages(host)
        collect_log_file(host, "/var/log/monitor-ssh-reboots", crashinfo_dir)
        collect_command(host, "dmesg", os.path.join(crashinfo_dir, "dmesg"))
        collect_uncollected_logs(host)


# Load default for number of hours to wait before giving up on crash collection.
HOURS_TO_WAIT = settings.settings.get_value(
    'SERVER', 'crash_collection_hours_to_wait', type=float, default=4.0)


def wait_for_machine_to_recover(host, hours_to_wait=HOURS_TO_WAIT):
    """Wait for a machine (possibly down) to become accessible again.

    :param host: A RemoteHost instance to wait on
    :param hours_to_wait: Number of hours to wait before giving up

    :return: True if the machine comes back up, False otherwise
    """
    current_time = time.strftime("%b %d %H:%M:%S", time.localtime())
    if host.is_up():
        logging.info("%s already up, collecting crash info", host.hostname)
        return True

    if hours_to_wait > 0:
        logging.info("Waiting %s hours for %s to come up (%s)",
                     hours_to_wait, host.hostname, current_time)
        if not host.wait_up(timeout=hours_to_wait * 3600):
            logging.warning("%s down, unable to collect crash info",
                            host.hostname)
            return False
        else:
            logging.info("%s is back up, collecting crash info", host.hostname)
            return True
    else:
        logging.info("Skipping crash info collection")
        return False


def get_crashinfo_dir(host):
    """Find and if necessary create a directory to store crashinfo in.

    :param host: The RemoteHost object that crashinfo will be collected from

    :return: The path to an existing directory for writing crashinfo into
    """
    host_resultdir = getattr(getattr(host, "job", None), "resultdir", None)
    if host_resultdir:
        infodir = host_resultdir
    else:
        infodir = os.path.abspath(os.getcwd())
    infodir = os.path.join(infodir, "crashinfo.%s" % host.hostname)
    if not os.path.exists(infodir):
        os.mkdir(infodir)
    return infodir


def collect_log_file(host, log_path, dest_path):
    """Collects a log file from the remote machine.

    Log files are collected from the remote machine and written into the
    destination path. If dest_path is a directory, the log file will be named
    using the basename of the remote log path.

    :param host: The RemoteHost to collect logs from
    :param log_path: The remote path to collect the log file from
    :param dest_path: A path (file or directory) to write the copies logs into
    """
    logging.info("Collecting %s...", log_path)
    try:
        host.get_file(log_path, dest_path, preserve_perm=False)
    except Exception:
        logging.warning("Collection of %s failed", log_path)


def collect_command(host, command, dest_path):
    """Collects the result of a command on the remote machine.

    The standard output of the command will be collected and written into the
    desitionation path. The destination path is assumed to be filename and
    not a directory.

    :param host: The RemoteHost to collect from
    :param command: A shell command to run on the remote machine and capture
        the output from.
    :param dest_path: A file path to write the results of the log into
    """
    logging.info("Collecting '%s' ...", command)
    devnull = open("/dev/null", "w")
    try:
        try:
            result = host.run(command, stdout_tee=devnull).stdout
            utils.open_write_close(dest_path, result)
        except Exception as e:
            logging.warning("Collection of '%s' failed:\n%s", command, e)
    finally:
        devnull.close()


def collect_uncollected_logs(host):
    """Collects any leftover uncollected logs from the client.

    :param host: The RemoteHost to collect from
    """
    if host.job:
        try:
            logs = host.job.get_client_logs()
            for hostname, remote_path, local_path in logs:
                if hostname == host.hostname:
                    logging.info("Retrieving logs from %s:%s into %s",
                                 hostname, remote_path, local_path)
                    host.get_file(remote_path + "/", local_path + "/")
        except Exception as e:
            logging.warning("Error while trying to collect stranded "
                            "Autotest client logs: %s", e)


def collect_messages(host):
    """Collects the 'new' contents of /var/log/messages.

    If host.VAR_LOG_MESSAGE_COPY_PATH is on the remote machine, collects
    the contents of /var/log/messages excluding whatever initial contents
    are already present in host.VAR_LOG_MESSAGE_COPY_PATH. If it is not
    present, simply collects the entire contents of /var/log/messages.

    :param host: The RemoteHost to collect from
    """
    crashinfo_dir = get_crashinfo_dir(host)

    try:
        # paths to the messages files
        messages = os.path.join(crashinfo_dir, "messages")
        messages_raw = os.path.join(crashinfo_dir, "messages.raw")
        messages_at_start = os.path.join(crashinfo_dir, "messages.at_start")

        # grab the files from the remote host
        collect_log_file(host, host.VAR_LOG_MESSAGES_COPY_PATH,
                         messages_at_start)
        collect_log_file(host, "/var/log/messages", messages_raw)

        # figure out how much of messages.raw to skip
        if os.path.exists(messages_at_start):
            # if the first lines of the messages at start should match the
            # first lines of the current messages; if they don't then messages
            # has been erase or rotated and we just grab all of it
            first_line_at_start = utils.read_one_line(messages_at_start)
            first_line_now = utils.read_one_line(messages_raw)
            if first_line_at_start != first_line_now:
                size_at_start = 0
            else:
                size_at_start = os.path.getsize(messages_at_start)
        else:
            size_at_start = 0
        raw_messages_file = open(messages_raw)
        messages_file = gzip.GzipFile(messages + ".gz", "w")
        try:
            raw_messages_file.seek(size_at_start)
            shutil.copyfileobj(raw_messages_file, messages_file)
            raw_messages_file.close()
        finally:
            messages_file.close()

        # get rid of the "raw" versions of messages
        os.remove(messages_raw)
        if os.path.exists(messages_at_start):
            os.remove(messages_at_start)
    except Exception as e:
        logging.warning("Error while collecting /var/log/messages: %s", e)
